#!/bin/bash euler_phi() { prime_factors=($(factor $1 | cut -d ' ' -f2- | tr ' ' '\n' | sort -u)) t=$1 for i in ${prime_factors[@]} do t=$(($t/$i*($i-1))) done echo $t } sum=0 i=2 while [[ $i -le 1000000 ]] do sum=$(($sum+$(euler_phi $i))) i=$(($i+1)) done echo $sum